There have been several reported methods for producing heavy oil-based or light oil-based hydrocarbons, so-called biofuels, through the culture of microalgae.
Regarding algae capable of producing heavy oil-based hydrocarbons: a microalga, Botryococcus braunii, which is capable of producing a hydrocarbon of 36 carbon atoms (refer to Non-patent Document 1); and a microalga, Botryococcus braunii race A, which is capable of producing a hydrocarbon of 33 carbon atoms (refer to Patent Document 1); have been known.
Moreover, regarding algae capable of producing light oil-based hydrocarbons: microalgae, Nostoc muscorum, Trichodesmium erythaeum, Plectonema terebrans, and the like, which are capable of producing a hydrocarbon of 17 carbon atoms (refer to Non-patent Document 1); a microalga, Coccochloris elabens, and the like, which are capable of producing a hydrocarbon of 19 carbon atoms (refer to Non-patent Document 1); a microalga Pseudochoricystis ellipsoidea strain MBIC11204, which is capable of producing hydrocarbons of 17, 18, 19, and 20 carbon atoms (refer to Patent Document 2); and a microalga, Choricystis minor stain SAG17.98, which is capable of producing hydrocarbons of 17, 19, 21, and 23 carbon atoms (refer to Patent Document 2); have been known.
Light oil-based hydrocarbons that can be produced by microalgae are industrially useful as a diesel fuel, and also show promise as a carbon neutral fuel intended for the prevention against global warming.
However, the content percent of light oil-based hydrocarbons in the dried algal biomass produced by drying the microalgae is usually about 0.025 to 0.12% by mass (refer to Non-patent Document 1), meaning that the hydrocarbon productivity thereof is not always sufficient.